The social effects caused by Zhang-disease in Ming and Qing Dynasties weakened because of diminution of this disease which is inseparable from population growth and immigrant,land cultivation and economic development,headman regulations and bureaucratization of native officers,climate changes and prevention technology improvement.
瘴气由气候和环境的恶劣而产生,而最终又随着气候的变迁和环境的改善而逐渐地消减、消亡。
The malaria region retreated from the hinterland to piedmonts and river valleys.
瘴气区域的变迁反映了生态环境变迁的状况。